Who is "extreme" on abortion?

In the wake of Todd Akin's idiotic and insensitive (albeit quite overhyped in the press and by partisans) recent remarks, and following up on Robby's post about the strikingly abortion-and Akin-centric character of the developing Democratic Convention schedule, it seems worth remembering who is actually in, and out, of the "mainstream" when it comes to the morality and regulation of abortion.